Fuel supply system



Oct. 1l, 1960 w. J. GLAssoN FUEL SUPPLY SYSTEM Filed Aug. 19, 1957 /N VEN TOR W/LL/AM J. GLASSON .N .m um

.TIEN a y Jl il A T7'ORNE'Y refr 1.

FUEL SUPPLY SYSTEM William J. Glasson, Los Angeles, Calif., assigner to Hughes Aircraft Company, Culver City, Calif., a corporation of Delaware Filed Aug. 19, '1957, Ser. No. 679,796

1 Claim. (Cl. 60-35.6)

purpose is a monopropellant fuel, ethylene oxide, which p is driven under high pressure into a reaction chamber 'through -a nozzle. The gases produced as a result of decomposition of the fuel in this instance are used to drive a high speed turbine. A relatively large amount of fuel must be delivered in an extremely short period of time, and it must be metered accurately to obtain proper performance of the chamber.

In my co-pending application entitled, Expulsion-Bag Tank for Liquid Propellant, Serial No. 678,760, tiling date August 15, 1957, means are described for storing the propellant under pressure and for releasing it at a predetermined time. The preferred timing sequence is related to -the requirement that the reaction chamber into which the fuel is to be introduced, must be preheated to la certain temperature before the propellant is permitted p to enter.

The Vpreheating is accomplished by the use of an explosive squb red electrically. The explosion of the squb builds up a relatively high temperature (above 1000 degrees Fahrenheit) and a pressure of the order of 500 p.s.i., in the reaction chamber. The temperature of about 1000 degrees Fahrenheit is necessary to initiate the reaction of the ethylene oxide. The fuel pressure rises to the order of 740 p.s.i. and the temperature to about 1800 degrees Fahrenheit upon the injection of the fuel.

A United tates Patent Patented Oct. 1 1, 1 960 prove the propulsive machinery required to drive airborne missiles and similar devices.

A further object is to provide means for feeding fuel into a reaction chamber subjected to substantial pressures and high temperatures while positively preventing preignition of the fuel.

A further object is to prevent the release of fuel into a reaction chamber until the chamber has been pressurized and properly heated to insure proper initial reaction conditions for the fuel.

These and other objects will be apparent from the a companying drawings, in which:

Fig. 1 is a schematic sectional view of a fuel system involving the principles of this invention, showing the seal-piercing mechanism in unactuated position;

Fig. 2 is a fragmentary sectional schematic Viewv of-the invention showing a later stage of operation in which the seal-piercing mechanism has been actuated so that fuel may ow to the reaction chamber; and

Fig. 3 is a graph showing the relations of chamber pressure to time during the early stages of operation.

Referring now to the drawings for a more detailed lexplanation of the invention, -there has been shown in Fig. l an assembly comprising a fuel storage tank 1, a control valve arrangement 2, and a reaction chamber 4. The

storage tank 1 has therein a fuel, such as ethylene oxide,I

It is essential that firing of the squb be completed before 4 A the fuel is injected, or there may be an explosion which will destroy not only the propulsion means, but the rocket carrier associated therewith. Electrical control of the squb firing simultaneously with application of current to a magnetically operated valve-opening mechanism is followed by operation of gas-operated seal-piercing means which release the propellant from its storage chamber. The pressure to operate the seal-piercing device is provided by the gases generated by the` tiring of the squb. A suflicient delay results from the inertia of the piercing mechanism to insure that the propellant flow under its delivery pressure of 'approximately 840 p.s.i. through an appropriate fuel injection nozzle will occur only after the squb has completely exploded within the reaction ch'amv which may be retained under its own vapor pressure of approximately 50 p.s.i. by means of a spring-held outlet valve 5, in combination with a sealing diaphragm 6 at the outlet end, and by a diaphragm 7 at its inlet end. An inilatable bag 9 for rupturing the diaphragm 7 is'contained thereby at the inlet end.

In a prior filling operation, the propellant fuel, which may be ethylene oxide, is forced through an inlet conduit 10 into the tank 1, where it is retained under pressure by means such as ya cap 11. As described in my co-pending application referred to above, the ethylene oxide chemically attacks all known materials that are practical for forming Aan inflatable bag which might be used to force it out of the storage tank and into the reaction chamber. The result of such chemical attack is a deterioration of the bag which leads 'to its unserviceability in a relatively short period of time. In the invention described, however, means were shown for separating the bag from the propellant fuel until the moment of discharge. The inllatable bag, which is commonly made of neoprene, or the equivalent, is thus in contact with the ethylene oxide for so short a time Vthat the corrosive nature of the latter does not produce any failure of fuel delivery.

Hence, when the bag 9 is expanded by forcing thereinto an inert gas, such las nitrogen, under pressure through the inlet conduit 8, the diaphragm 7 is ruptured. The bag then expands to iill .the tank, forcing the propellant liquid out through the valve 5, that will hereafter be Open in accordance with the preferred timing sequence described below. After passing through valve 5, the propellant travels through the central passage 12 and the transverse passage 13 o-f the piercing spear Vll, thence through an annular chamber through conduit 16 to a nozzle 17 lthrough which it is sprayed into the reaction chamber 4. Within the'reaction chamber, high pressure of approximately 200-500 p.s.i. andtemperature in, excess of 1000 degrees Fahrenheit, causes the ethylene oxide to react, and the resultan-t pressure produced forces it out through the exhaust pipe 19 and nozzle 20 into the turbine equipment directly .responsible for the propulsion of the missile power supply.

It Will be appreciated that ifthe ethylene oxide is permitted to enter the reaction chamber prior to Ithe heating of the chamber by firing the squb, an explosion might occur which would destroy the entire mechanism. To avoid this possibility,

15 surrounding the spear, and thence v a simple timing sequence has been developed. The energization of the solenoid windings 21 associated with the valve 5, is accomplished simultaneously with the firing of the squib 22 by using means such `as common leads 24 and 25. This opens the valve piston 39 in readiness for the puncturing of the seal. There is sufficient time lag due to the inertia of the moving parts of the seal-piercing assembly 26, so that the firing of the squib 22 may be complete and the temperature within the reaction chamber 4 raised to above 1000 degrees Fahrenheit before the piercing spear 14 has moved sufficiently to cut through the sealing diaphragm 6. The piston head portion 27 of the seal-piercing assembly is forced to move by gaseous pressure from the squib communicated thereto from the reaction chamber through pressure conduit 29. There is, thus, a short delay time while the diaphragm 6 is being opened, sufficient that fuel cannot enter the reaction chamber until the desired chamber temperature has been obtained.

In the magnetic circuit, the valve S must be opened to make fuel flow possible prior to, or simultaneously with, the piercing of sealing diaphragm 6. Subsequent to the initial starting conditions, the valve is used to meter the flow of fuel to the chamber to control the desired power delivered to the turbine, not shown, which supplies electrical power for the operation of the missile during flight. The arrangement for accomplishing this opening includes a complete magnetic circuit, a portion of which is formed by the tank 1 and its associated parts, and a portion of which is formed by the assembly which in corporates the seal-piercing means. The complete magnetic circuit includes, in addition to the piston 39, the mounting flanges 40 in which it is slidably disposed. Both of these parts are formed of high permeability magnetic material. The annular flange member 40 is secured to the tank 1. A forward extension of the flange 40 and of diameter reduced to the order of that of the cylinder 41 in which the piston 39 is slidably disposed, acts as a set for the forwardly extending annular portion 30 of the control valve arrangement 2 which extends thereabout and within the solenoid windings 21. The complete closed magnetic circuit thus includes the solenoid windings 21, the annular flange member 40, which is formed of high permeability magnetic material, the slidable valve member 39, the annular portion 30, and a solenoid enclosing member 44 which completely encloses the solenoid windings. The llux concentration with this arrangement is indicated by line 52 in Fig. 1 and will be such as to produce an axial movement of the slidable piston valve member 39, to open or close against central bore 45, leading toward the sealing diaphragm 6.

.As described in the pending application referred to above, the resilient spring member 46, which is disposed in compression between a screw plug 47, seated threadably in the end wall of tank 1, exerts a force against the valve 39 which tends normally to keep a magnetic projecting valve end 49 sealed against the entrance to central bore 4S. When the magnetic circuit -is energized, however, the piston is withdrawn against the spring pressure to open the passageway to the sealing diaphragm 6, and to act as a metering device for propellant flow. The seal provided by the valve itself, while suitable for metering purposes, is not satisfactory for storage purposes or to insure that no propellant leaks into the reaction chamber before the desired time. Hence, the rupturable seal is required for this reason, in addition to being required as part of the previously mentioned timing sequence.

When the squib 22 is tired, it immediately builds up the pressure and temperature within the reaction chamber 4, as indicated by the solid line 50 in Fig. 3. The pressure range is normally between 200 and 500 p.s.i. for this portion of the operational sequence. After pressure has been built up to a suicient value, the pressure in reaction chamber 4 forces the piston 27 to move, driving the hollow spear through the sealing diaphragm 6, and permitting the fuel within the pressure tank 1 to be driven out through the now open piston 39, through the annular chamber 15, conduit 16 and nozzle 17, into the reaction chamber. This effect occurs because the pressure supplied to the bag 9 is of the order of 840 p.s.i., which is in excess of the 200 to 500 p.s.i. existing in the reaction chamber 4 at this time. As soon, however, as fuel has been forced into the reaction chamber 4, at the point on the curve indicated as 51 in Fig. 3, the reaction pressure begins to build up to a value of approximately 740 p.s.i. This chamber operating pressure may be varied by controlling the flow of propellant by the solenoid valve toA produce the desired turbine output. The pressure so created drives lthe fuel out through the exhaust pipe 19 and nozzle 20 where it is delivered to a gas turbine, not shown, which drives means for generating the electrical power required to operate various components of the device during flight.

It will be obvious that variations in the specified parameters will occur, depending on such factors as the exact pressure applied through the inflatable bag to force the propellant out of the tank and into the reaction chamber, the required operating pressure of the reaction chamber, and the exact temperature and pressure built up before the entry of the fuel into the reaction chamber.

It will be apparent from the discussion above that this invention has provided means for insuring a safe timing sequence in the supplying of liquid fuel to the reaction chamber of a propulsive arrangement or electrical power source for a rocket or similar device in which the reaction chamber is preheated to a value necessary to successfully proceed with the fuel reaction but in which premature entry of the fuel which might result in `an explosion damaging the equipment, is prevented.

What is claimed is:

In a fuel delivery control apparatus for use between a bladder pressurized fuel tank and a combustion chamber, the combination of: conduit means extending between said tank and said combustion chamber; a control apparatus body forming a portion of said conduit means; a firing squib positioned in said combustion chamber; a normally closed partition in said body; a solenoid operated valve positioned in said body intermediate said partition and said tank and normally closing said conduit means between said tank and said partition; tubular partition piercing means positioned in said body and adjacent said partition; means for simultaneously energizing said valve to an open position and said squib; a piston slidably disposed in said body and connected to said piercing means; and a conduit for conducting gas from said chamber to said piston means whereby to effect movement of said piston and said piercing means in responseto a pressure rise in said combustion chamber to a predetermined level, as induced by action of said squib upon ignition thereof, for moving said pierce means through said partition where-by to permit flow of said fuel through said conduit means to said combustion chamber.

References Cited in the le of this patent UNITED STATES PATENTS 2,402,826 Lubbock June 25, 1946 2,671,312 Roy Mar. 9, 1954 2,733,569 Trowbridge Feb. 7, 1956 2,740,259 Westlund Apr. 3, 1956 2,777,289 Boucher J an. l5, 1957 2,859,808 Youngquist et al Nov. 11, 1958 

